Argument 1 to "fields" has incompatible type "type[AttrsInstance]"; expected an attrs class

Bug Report

mypy is reporting that a type[attrs.AttrsInstance] is not a valid argument to attrs.fields

To Reproduce

from __future__ import annotations

import attrs


@attrs.define
class X:
    x: int


attrs.fields(X) # fine


def func(klass: type[attrs.AttrsInstance]) -> None:
    fields = attrs.fields(klass) # error
    print(fields)


func(X) # fine

Expected Behavior

% mypy x.py
Success: no issues found in 1 source file

Actual Behavior

% mypy x.py
x.py:15: error: Argument 1 to "fields" has incompatible type "type[AttrsInstance]"; expected an attrs class [misc]
Found 1 error in 1 file (checked 1 source file)

Your Environment

Mypy version used: 1.6
Mypy command-line flags: (w/ or w/o --no-incremental)
Mypy configuration options from mypy.ini (and other config files): default
Python version used: 3.10

I'm also seeing this in 1.6, but not 1.5.1.

I started seeing this when my mypy version jumped from 1.5.1 -> 1.6.1. No difference in my source code or attrs version. Code to reproduce:

import attr

@attr.s(frozen=True)
class MyClass(object):
    @classmethod
    def fields(cls):
        return attr.fields(cls)

we can then see:

$ .venv/bin/mypy test.py
exp.py:7: error: Argument 1 to "fields" has incompatible type "type[MyClass]"; expected an attrs class  [misc]
            return attr.fields(cls)
                   ^~~~~~~~~~~~~~~~
Found 1 error in 1 file (checked 1 source file)

I'm also seeing this in 1.6, but not 1.5.1.

I am too. However, I tested with the latest from master, and it seems to be fixed 🤞. So I would expect the fix to be included in the next release.

This was fixed in #15983.

Do you know if we will get a 1.6.2 cut with this fix?

@hauntsaninja

Do you know if we will get a 1.6.2 cut with this fix?

Probably not; mypy 1.7 is expected soon, I believe. But @hauntsaninja has been managing patch releases for mypy 1.6, so it'll be up to him to decide

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Argument 1 to "fields" has incompatible type "type[AttrsInstance]"; expected an attrs class #16254

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Argument 1 to "fields" has incompatible type "type[AttrsInstance]"; expected an attrs class #16254

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Ranfir commented on Oct 12, 2023

awerchniak commented on Oct 19, 2023

jp-larose commented on Oct 24, 2023

ikonst commented on Oct 24, 2023

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